1. Field of the Invention
This invention relates to the field of data processing systems. More particularly, this invention relates to data processing systems that apply a plurality of tests to a target computer file, such as, for example, a plurality of anti computer virus test to scan a suspect computer file for computer viruses.
2. Description of the Prior Art
It is known to provide anti computer virus programs that apply a plurality of tests to a suspect computer file to identify if it contains a computer virus. As new computer viruses are released, tests to detect those computer viruses are developed and added to the list of tests that an anti computer virus applies to a suspect computer file. As the number of known of computer viruses increases, then the number of tests required also increases. Typical anti computer virus programs at the current time potentially apply tests for up to 60,000 different known computer viruses. The amount of computer processing resource required to perform these tests is large and ever-increasing.
There are various different types of computer virus. Some computer viruses infect only executable EXE and COM computer files, whereas other computer viruses may be macro viruses or embedded HTML viruses that only infect different file types. When a scanning engine receives a request to scan a particular computer file, then it is known to arrange that the scanning engine will select only those test drivers that check for computer viruses that could possibly infect that type of computer file, e.g. there is no point in checking an EXE file for an embedded Word macro virus.
Measures that can reduce the processing load associated with anti computer virus defence mechanisms and increase the efficiency and effectiveness of protection against computer viruses are strongly advantageous.